Keywords Used in Spartan

Keywords specific to the conformational module
CONFANAL* Do a conformational search producing multiple results.
SCONFANAL* Do a conformational search producing only a single, lowest energy, result.
SLCONFANAL* Menu command to generate a library of conformers. Similar to combining the following keywords: SCONFANAL SEARCHMETHOD=SYSTEMATIC REPRUNECONFS=11,15,0.75
  • SYSTEMATIC to force the systematic algorithm.
  • MONTECARLO or MC to force the Monte Carlo algorithm.
  • THOROUGH to increase the default bond-rotation by a factor of three, and also set the KEEPALL keyword.
  • SPARSE Use the Systematic-sparse method searching for 2000 randomly selected conformers. See the SPARSE= keyword for more information.
  • REREAD Re-read a previous run which has deposited result in the proparc file with the SAVEINPROPARC option. This is useful in trying different pruning options (see PRUNEMETHOD) on a KEEPALL run.
SYSTEMATIC for smaller, less flexible systems.

MONTECARLO for larger more flexible systems.
Set the maximum number of returned conformers to N. The program attempts to select the most diverse set representing the entire population within the energy 100
WINDOW= Sets the maximum (delta) energy at which a trial conformer will be saved in the data set. Conformers with an energy greater than the current minimum energy plus this value are rejected. 10.0 (kcal/mol)
KEEPALL Keep all generated conformations. This is similar to maximizing MAXCONFS and WINDOW options, but will also keep some conformers typically thrown away because of bond strain.
Maximum number of attempted molecules. Only meaningful for the MONTECARLO method. This is controlled from the "Maximum Conformers Controlled" entry in the setup panel. A complicated function. see How many cycles...
MCCONFS= The Monte Carlo algorithm will do this number of steps, overriding the "Maximum Steps" and the default count.
Changes the default 6-member ring move (cyclohexane) to attempt to find the twist-boat conformation. This dramatically slows down the algorithm as the number of possible moves changes from 2 to 27. If FINDBOATS is used the WINDOW= value is increased to 15 kcal/mol as twist-boat conformations are typically higher in energy (~6 kcal/mol for cyclohexane). off
SKIPBOATS Uses the fast cyclohexane move of correlated flips. on
STARTTEMPERATURE= The initial temperature for the monte carlo/simulated-annealing algorithm. 5000 K
NORIGID Do not attempt to do any 'rigid moves' but rely on constraints to get the correct structure. This will likely slow down the algorithm.
NOOPT Do only rigid moves and single points. Do not attempt to re-minimize. (Only useful for small "dynamic constraint" systems).
IGNORENOES Ignore any NOE constraints in the system. The default is to use the NOE constraints as a filter only.
CONSTRAINNOES Pass any NOE constraints on to the optimization engine. (Currently only supported by mechanics.) Thus all intermediate results satisfy the NOE constraints. The default is to use the NOE constraints as a filter. This can lead to some highly strained conformations and is not advised for most conformational searching, but can be usefull in some geometry optimization cases.
NOEBIASE= Used to bias the energy to favor conformations that satisfy the NOE constraints. By default this is turned off. Must be a positive number. 0.0 (kcal/mol)
SAVEINPROPARC Instead of generating a new list of conformers save the conformers in the property archive for use in Spartan's database applications or the "Similarity Library/Analysis" modules.
PRUNEMETHOD=i Select a different algorithm when deciding which of the conformers to be saved.
  1. Default method of pruning out higher energy conformers, and attempting to keep a diverse set of the low energy conformers using the RMS-torsion definition of nearness.
  2. Use a binning algorithm using the moments of inertia [(3*Ismall/Itot)^2], polar surface area, dipole, and internal dihedrals as measures of diversity.
  3. 2 .. 9 are small variants on the binning algorithm (not tested yet).
  4. Use a cluster algorithm, which is controlled by the DISTANCEMEASURE keyword.
  5. Modified version of 10 but attempt to keep the central molecule in a cluster, as opposed to the 'lowest' energy in a cluster.
(The default is 0.)
Rerun the pruning algorithm as a property calculation. the optional i. i. tol are values for the PRUNEMETHOD=i, DISTANCEMEASURE=j, and DISTANCEISNEAR=tol keywords, respectively. This keyword is a 'property' keyword, and can only be used after a main conformation run which has been executed with the SAVEINPROPARC keyword.
DISTANCEMEASURE=i A scalar number used to measure distance between conformers.
  1. Using differences in the torsion values of important dihedrals. (The default.)
  2. Use the RMS xyz distance of the heavy atoms of a molecule moved to minimize this RMS value.
  3. Use the RMS xyz distance of the heavy atoms of a molecule aligned to the maximally aligned structure.
  4. Use the score of the maximally aligned structure.
  5. Use the number of atoms not aligned in the maximally aligned structure. Then add (1-normalized-score) to discriminate among conformers with same number of 'aligned' atoms.
  6. Use the number of atoms not aligned in the RMS-xyz distance aligned structure
  7. 11,12,13,14,15,16 Use a pharmacophore structure for alignment, as opposed to the atomic structure used in 1,2,3,4,5,6.
The "maximally aligned structure" and it's score is discussed in the align FAQ.
PRUNETOLERANCE=x In the cluster pruning algorithms conformers are considered "near" if they are within this value. If this value is set to zero, this tolerance is not used, and the nearest pairs will be pruned until the number of conformers desired is reached. See DISTANCEMEASURE for the units and definition of distance used in these algorithms. 0.0
SPARSE=x A modification of the systematic search, where a (random) subset of the systematic conformers are tried. If X > 1 then a total of X (random) conformers will be attempted. If X < 1 then a fraction (x) of the total conformers will be attempted.
CONF_SELECTION_RULE=i* There are a number of default rules used to determine which bonds to rotate. These rules are split into different classes, each of which is useful for different types of problems.
Rules used for all rule sets are:
  • Do not rotate bonds around ligand points (such as the Cp ligand)
  • Do not rotate around double bonds.
  • Do not rotate amide bonds
  • Do not rotate around symmetric bonds such as -CH3 and benzene rotors
There are currently 5 sets of rules:
  1. Legacy Spartan 02 rule set.
    • Do not rotate amide bonds
  2. Legacy Trident rule set used in the pharmacophore searching algorithm
    • Do not rotate ester bonds
    • Do not rotate around terminal xH bonds, such as -OH or -NH2.
  3. Normal.
    • Do Not rotate ester bond
    • Rotate amide bond
    • Do not attempt to find twist boat conformations.
    • Attempt to recognize when different conformation of chair like rings (cyclohexane) can be reproduced by a single rotation.
    • Recognize affects of fused rings
  4. Skeletal is an extension of the 'Normal' mode but designed to be quicker by only finding 'important' minima.
    • Do not rotate around terminal xH bonds, such as -OH or -NH2.
    • All bonds to nitrogen are given a fold of 2, even if they formally have a 3-fold rotation.
    • Do not rotate carboxylic acid groups.
    • Do not rotate methoxy groups and ethane groups when attached to benzene.
    • Do not search for multiple conformations of piperazine.
    • Do not rotate long alkyl chains.
  5. Exhaustive is an extension of 'Normal' mode, but designed to find even high energy minima.
    • Rotate ester bonds
    • Attempt to find boat conformations of cyclohexane like rings.
    • Attempt to find conformations of constrained 5 and 6 member rings.
  6. Normal12 Deprecated. The default value in iSpartan (our iPad/tablet product).
  7. Thorough is an extension of 'Normal' mode, but designed to find even high energy minima.
    • Flips some non-planar nitrogens

In Spartan 18 we've added a series of rules and algorithms to better deal with rings with more than 6 flexible bonds. These new methods are noted by adding the "(rings)" postfix in the Preferences/Settings Panel for the keyword by adding 10 to the rule integer (i.e. 13 is Skeletal with rings).

Spartan ships with the default of "12" set in the preference panel. If you were to use this as a keyword you could either use CONF_SELECTION_RULE=12 or CONF_SELECTION_RULE=NORMAL+RINGS.

This value can be set as a keyword, or as a system wide preference in Spartan's preference dialogue (Options Menu). It is important to remember that the selection rules are overridden when users specify atoms/bonds from the 'Set Torsions' mode. Thus this keywords should seldom be used and instead use the default and examine each molecule via the (Menu -> Geometry) "Set Torsions" mode.

If you are using this keyword it should likely be combined with the IGNORE_USERSELECTION keyword.

IGNORE_USERSELECTION Ignore the bond selection from the user (via the Menu -> Geometry"Set Torsions" mode). Instead use the default rules for determining rotatable bonds. (User defaults are set whenever the user enters the 'set torsions' mode.)
DRYRUN Execute only the setup part of conformational analysis. This is only used in debugging.
DISTANCEMEASURE=i Measure to use in determining distance between two conformers.
TRACK_DOUBLE=NO Double bonds to rotate (greater than 90 degrees) even if not selected as flexible rotors. YES
TRACK_CHIRAL=NO Allow atoms to change chirality. YES
CONFSEED= The starting point for the random number generator.
keywords passed to underlying method
FREQ* Will do a frequency calculation on the final candidates.
ANHARMONIC An extra second-order vibrational perturbation theory (VPT2w) and a Transition-optimized shifted Hermint (TOSH) calculation will be done to get c
ANHAR=TRUE allow anharmonic calculation. (Job must be a single-point energy only calculation with the frequency property checked). Combine with the VCI= keyowrd to run a VCI calculation.
VCI=n The number of quanta involved in a Vibration Configuration Interaction (VCI) calculation.

MODE_COUPLING=n The number of modes coupling in the third and fourth derivatives calculations.

IGNORE_LOW_FREQ=300 Low frequencies that should be ignored during anharmonic correction calculation. (i.e. assumed rotational) 300 cm-1
VIBMAN_PRINT=n n can be 1 .. 6 and increase the amount of vibrational (and anharmonic information) printed in the verbose output. Use with the KEEPVERBOSE in order that this information is not deleted.
PRINTLEV= Control Printing. See Description of the output file for more information.
PRINTLEV=2 displays a label for each conformation.
PRINTLEV=3 dumps the intermediate minimization output to the main output window
...other keywords... Keywords unrecognized by the conformation and energy profile module will be passed to the underlying method. See below for some commonly used keywords.
Keywords specific to the energy profiles
Do dynamic constraints/Energy Profile.
SDYNCON Do a energy profile but only return one result. (Usually, this result is a transition state, but if no local maxima exist the local minima will be returned.) This is not a recommended option, and is used primarily for debugging purposes.
DYNCONMETHOD= If there are multiple constraints how are these constraints applied
  • SEQUENTIALly. First one then the next.
  • On a grid GRID, such as a phi-psi plot. or
  • TOGETHER, where both constraints are adjusted in concert with each other.
KEEPSYMMETRY Attempt to maintain the starting molecule's symmetry.
NORIGID Do not attempt 'rigid moves' but rely on constraints to get the correct structure.
NOOPT Do only rigid moves and single points. Do not attempt to re-minimize.
NOMECHPREOPT Do not prefix each minimization with a mechanics constrained optimization. This is only meaningful for non-mechanic's methods such as AM1.
RIGIDONLY Do only rigid moves and single points. Do not attempt to re-minimize. (Only useful for small "dynamic constraint" systems).
Save temporary files. Useful for debugging. SAVEFILES=2 (or greater) will save even more intermediate files including those of the sub-jobs.
SAVETEMP= Not-implemented
NAMEPREF=abc Save conformers (or energy profile steps) using the name 'abc'. (This will force the creation of a new file even if executing a 'Equilibrium Conformer' job.
REPLACE Not-implemented
*   Keywords marked with an asterisk '*' should not be typed in. They are generated by the setup panel.
Other useful keywords for the energy profile module
Keywords not recognized in the conformer/energy-profile module will be passed on the underlying method. Following are some keywords found to be useful.
(mechanics only)
Add the solvent model as a final perturbation. Thus, all minimizations are done with the base force field and a solvation 'correction' is applied to the final energy. SM50R is the most used mechanics solvation model. (POSTSOLVENT=SM50R)
Geometry Optimization Keywords
How many geometry steps to try before failing. If you are having difficulty converging this can be increased. However if the job is continually running out of cycles it may be an indication that either the starting geometry was far from a good starting point, or that something unexpected (like forming a new bond and/or breaking a bond is occurring. (OPTCYCLES= is a deprecated pseudonym for this keyword.)
The maximum gradient on any atom must be less than this amount.=.0007
The maximum predicted relative atomic movement must be less than this amount (in bohrs). =.00002
The energy difference from the previous step must be less than this amount (in hartrees)=.000001
GEOMTOL=* A short cut for various geometry tolerance settings:
label GradientTolerance DistanceTolerance EnergyTolerance
=DEF16 0.000300.0012.0000010
=TIGHT 0.000095.0008.0000010
=DEF 0.000700.0014.0000200
=LOOSE 0.000800.0015.0000762
The geometry is considered 'converged' when two of the three conditions are met. Typically the gradient condition is the most sensitive.
NOGEOMSYMMETRY This turns off the use of symmetry in the optimizer. This includes "local-atomic" symmetry used in the geometry optimizer which recognizes that sp3 carbons are roughly tetrahedral, and sp2 carbons are roughly planar. This can slow down the optimization by a factor of two, but in difficult cases such as highly coordinated atoms or large geometry changes this can help convergence.
HESS=UNIT Instead of using the default hessian, use a simple 'unit-diagonal' hessian. If you don't trust the current/previous hessian this is an option. It is never a great approximation of the true hessian but it is never 'very-bad'.
Controlling the ESP (electrostatic potential) algorithm
SHELL= The farthest extent of the shell of points to used to fit the electrostatic potential. 5.5 bohrs
WITHIN= A buffer between the standard vdW radii and the nearest points in the shell of external points. 0.0 bohrs
ELCHARGE= An integer number representing the number of points per cubic Bohr. 1
NOELCHARGE Skip the electrostatic charge calculation.
CHELPDENSITY= An integer number representing the number of points per cubic Bohr. 1
SVD= Use the CHELP-SVD (Single value decomposition) algorithm to calculate the charges. Setting to 0 turns off. There are a number of variants to this algorithm:
  1. An older, deprecated, algorithm.
  2. Don't prune points.
  3. Attempt to prune terms (vectors) which do not significantly improve the accuracy.
CHELPPOINTS= Algorithm which places points into the shell.
  1. Use a rectangular grid.
  2. Use a spherical grid with approximate constant density.
  3. Use a spherical grid with density decreasing ~1/radius.
CHELPEXTRA= Choose more points than just nuclei. This allows one to approximate a multipole expansion around each nuclei.
  1. Use 1 point per nuclei.
  2. Use 7 points per nuclei.
  3. Use 10 points per non-hydrogen nuclei.
  4. Use 14 points per non-hydrogen nuclei.
  5. Use bond orientated, atom centered dipoles
  6. Modified version of model 4 adding extra points on atoms with 2 bonds.
  7. same as 5, but add dipoles to hydrogens
  8. Dipoles on all terminal atoms
  9. A flag to cycle through all models
By default electrostatic charges are reported using method '0'. However, points using method '2' are also calculated and available to be used.
CHELPPRINT=i Print more information about the ESP charge calculation. Integers greater than 1 cause successively more printing. Also available is TERSE 1
Keywords to analyze the wave-function
PRINTMO1 Print the Molecular orbitals.
Print molecular orbital energies.
Delete unoccupied molecular orbitals 'x' above the LUMO. This is useful in decreasing the size of the molecular data stored on the disk and in making the output of PRINTORBE and PRINTMO more reasonable. 10
POSTHF Use the post Hartree-Fock wave function if available. On by default for MP2 type calculations.
NOPOSTHF Do not use the post HF calculations. For MP2 this means, to use the HF wave function instead of the corrected MP2 wave function,
IGNOREWVFN Skip all wave function dependent properties.
Do the natural bond order hybridization analysis. See the above discussion. Possible values for yy are:
  1. NORMAL, the default.
  2. IONIC to see ionic contributions.
  3. 3C to examine three-center contributions.
Print the Mulliken charges. With a value of 3, the full matrix is printed,1
Skip the Mulliken charge calculation.
POP1 Print the natural atomic charges.
NONATCHARGE Skip the natural atomic charge calculation
Print a summary of charges and bond order. A (much) shortened version of what is printed with the MULPOP, POP, BONDORDER and NBO keywords. If x=1 only atomic charges are printed. If x=2 Mulliken bond orders are shown. If x=2 natural bond orders are shown.
DEORTHOG Deorthogonalize semi-empirical MOs before calculating properties.
DIPOLE Print out the Cartesian components of the dipole moment.
NODIPOLE Skip the calculation of the dipole moment.
BONDORDER Print out Mulliken and Lowdin bond order matrices, plus atomic and free valences for open-shell wave functions.
PRINTNBO Print the AO to NBO transformation
NOPOP Skip the natural bond order (NBO), and natural charge calculation.
DOEPN Print out the "Electronic Potential at Nuclei" for Oxygen and Nitrogen. DOEPN=SKIP to skip calculation. (By default the calculation is stored in archive but not printed. Enter DOEPN=ALL to print all atoms.
PRINTS Print the atomic orbital overlap matrix (S).
LOGP= See the discussion on the logP calculation
ELP Specify that the elpot+polpot grid will be used to generate atomic charges. This is valid for closed-shell HF-only molecules.
Print the overlap matrix as a lower triangle. Use in conjunction with the PRINTMO keyword if you want to do your own 'home-brew' quantum mechanics calculation. See the discussion of atomic orbitals for more information. (The PRINTS spelling is deprecated.)
POLAR Calculate the static polarizability of the molecule. For Hartree-Fock and semi-empirical methods this will also calculate the static hyperpolarizability. See our discussion above for more details on how to calculate polarizability.
HYPERPOLAR Calculate the static polarizability and hyperpolarizability of the molecule. Not available for DFT methods using pure basis sets (i.e. 6-311G etc.).
Calculate the polarizability at different frequencies. There can be multiple frequencies, here represented by 'a','b', and 'c', but could be more (or fewer) comma separated values. UNIT should be replaced with au, nm, ev, hz or cmInv. For example:
Note that an energy of 'zero' (0.0) is a way of specifying the static (infinite wavelength) case.
POLAR=WALK,start,end,step,UNIT This format of the POLAR keyword allows one to specify a range of frequencies/energies. This WALK format is also available for the HYPERPOLAR keyword. As an example:
EMFIELD= Can apply an external (multipole) field to the main calculation. Thus allowing a numerical way of calculating static polarizability. One stipulate multiple comma separated Cartesian terms representing dipoles (X,Y,Z), quadrapoles (XX,XY,YY etc.). For example:
The units are in "atomic units". ie. 1 a.u. = 51.422 V/Å
Keywords related to frequencies and thermodynamics
NOFREQ Do not do any frequency or thermodynamic calculation even if there is a good Hessian. (By default, if a high quality Hessian is available, frequencies will be calculated.
Scale all the frequencies by a factor 'x'.
DROPVIBS=x When calculating thermodynamics values, ignore all modes with frequencies below 'x'.
When calculating thermodynamics values, clamp enthalpy terms at 'x'RT. (If no 'x' given 1/2 is used.) Entropy will be clamped at2x'x'R (i.e. R by default). For the default 'x'=1/2 these limits imply a break in the enthalpy and entropy near ~260 cm-1. To turn "clamping" off use CLAMPTHERMO=NO 0.5
PRINTMODE Print thermodynamic information for each mode.
TEMPERATURE= Change the default temperature used in the thermodynamic calculation. 298.15 K
TEMPRANGE=start,end,step Print thermodynamic properties for a range of temperatures.
PRESSURE= Change the default pressure used in the thermodynamic calculation. 1.0 atm
PRINTFREQ1 Print the Cartesian values of the normal mode vibrations. This is what the 'Print Vibrational Modes' button in the calculation dialogue.
THERMO1 Print standard thermodynamic data. This is the 'Print Thermodynamics' button in the calculation dialogue.
PRINTIR Print Infrared and thermodynamic information for each normal mode vibration.
PRINVIBCOORDS Print the coordinates of each vibrational mode.
By default Spartan uses the 'most common isotope' as the mass of atoms when doing thermodynamics calculations. (Changing the isotope of a specific atom in the property dialogue overrides the mass for only that atom.)
  1. AVERAGE: Use the terrestrial average mass.
  2. COMMON: use the most common isotope as the atomic mass. (This is the default in Spartan.) Isotope settings in the GUI will override this default value.
  3. STANDARD: use the average mass, and ignore any specific atomic mass settings set in the atom property panel.
APPROXFREQ Calculate frequency and thermodynamic information on the intermediate low quality Hessian. (Not recommended.)
GXTHERMO Calculate G3 type results. (Internal keyword, should not be used unless you know what you are doing.)
Calculate frequencies by numerical differentiation, using central differences (CD) or forward differences (FD) as opposed to analytically. Analytical methods are usually much faster and more accurate than numerical methods as numerical methods require 6 single point calculations for each atom in the molecule. Forward difference is usually %50 faster than central differences, but is significantly less accurate and is not recommended. The default is to use analytical frequencies if available.
NUMERICALFREQ Calculate frequencies by numerical differentiation, using central differences. Analytical methods are usually much faster and more accurate than numerical methods as numerical methods requires 6 single point calculations for each atom in the molecule.
FD=xx.yy2 Step size for numerical differentiation. 0.005 bohr
DORAMAN2 Calculate the Raman intensities along with the standard IR intensities.
General property keywords.
KEEPVERBOSE By default the verbose output file is deleted/pruned. (For many jobs this can dramatically decrease the size of .spartan files.) Instead of using this keywords, one can set the "Keep Verbose" check box in the "Preferences Panel".
For 'i' greater than 1, print more information into the output file. 'i' must be 4 or less.0
PRINTCOORDS Print the Cartesian coordinates of all atoms in the system.
ACCEPT Accept certain error conditions and continue without a fatal error.
BTABLE=BAD Print out a table on all bond distances (B), bond angles (A) and dihedral (D) angles. If only bond distances, angles or dihedrals are required, BAD can be replaced with B, A, or D respectively.
NEAREST=x.y Specify the multiplication factor (applied to nearest-neighbor distances) when generating the geometric information. 1.2
QSAR Prints various QSAR descriptors. While these values are usually calculated, and can be found in the proparc file and in the spreadsheet this prints them to the output file. The list of descriptors this keyword prints is:
  • Atomic Weight
  • E-LUMO and E-HOMO
  • Electronegativity, Hardness and Est. Polariz. (AM1 only)
  • Molecular Volume, Surface Area and Ovality
  • logP (Ghose-Crippen, Dixon, and Villar[SE only])
  • Exposed Surface Area
  • Atomic Valence
  • Q-minus and Q-plus (for any charges)
  • Free Valence
  • Total Overlap Population (ab initio only)
NOQSAR Skip the calculation of QSAR descriptors.
MOMENTS Print out the moments of inertia, in both atomic units and inverse centimeters.
MAXVOLSIZE=i Atomic volumes and surface areas will be calculated only for systems with fewer than 'i' atoms. 100
SOLVRAD In calculation of atomic areas and volumes, add this value to the VdW radii.
To control the internal working of the volume calculator.
To select different solvation models. See the discussion on solvent methods and the SOLVENT= keyword.
TESTPROPS=1 Internal keyword used for debugging and QA work at Wavefunction. This works on the 'cell' data of the spreadsheet. Cells with the following names are analyzed:
  • Reference_E=xxx.yy ; The energy in Kcal/mol.
  • REF_PREC_E=x.yyy ; precision (default 5.0e-8)
  • PROP_x=Equation ; Most spreadsheet equations are valid
  • REF_PROP_x=xxx.yy ; the target value
  • REF_PREC_x=x.yyy ; precision (default 1.0e-4)
PARCFORMAT=i [for internal to Wavefunction use]
If i=1 write both formats of frequency information. If i=2 write only new format of frequency information.
Keywords related to the Intrinsic Reaction Coordinate (IRC) calculation
See How can I use the Intrinsic Reaction Coordinate procedure? for more details
IrcSteps=2 Specifies the maximum number of points to find on the reaction path. (Should be odd. The default value of 41 yields 20 steps forward and 20 backwards.) 41
IrcStepSize=2 Specifies the maximum step size to be taken. This is in thousandths of a Bohr. The default of 150 means 0.15 Bohr. 150
RPATH_TOL_DISPLACEMENT=2 Specifies the convergence threshold for the step. If the atoms are moving less than this value, configuration is assumed to be at a minima and the algorithm will stop. The units are in millionths of a Bohr. The default value of 5000 corresponds to 0.005 Bohr. 5000
Keywords for excited state and UV/Vis calculations
ESTATE=n1,2 Choose the excited state to calculate the gradient for. Usually this is not entered as a keyword, but is selected by choosing 'First Excited State' in the calculation dialogue. 1
TDA Use the Tamm-Dancoff approximation (TDA) to the standard Time Dependent DFT (TDDFT) algorithm. (The TDA was the default method for DFT calculations prior to Spartan'14v117.) This can be up to twice as fast as the default "Full TDDFT" and produces similar, but not as precise results. The TDA approximation also converges easier than the full TDDFT algorithm so may be useful in cases where convergence is difficult.
EXMULT= For excited states we typically keep the number of electrons the same as the ground state. This keyword can be set to =TRIPLET, =SINGLET, or =ANY to allow more flexibility in selecting the desired excited state.
CIS_N_ROOTS=2 To examine more orbitals in the excitation. For systems where there are many delocalized atoms you may want to increase this number from the default. Despite the "CIS" in this keywords spelling, it is also appropriate for TDDFT calculations. >=5
CIS_TRIPLETS=FALSE2 To limit the search of excited states to only singlets. Use this keyword only for excited state calculations. If this is used when doing an UV/Vis spectrum calculations this keyword will interfere with the INCLUDESINGLETS and INCLUDETRIPLETS keywords. =TRUE
UVSTATES=2 To examine more orbitals in the UV/Vis calculations. For systems where there are many delocalized atoms you may want to increase this number from the default. Only valid when the "UV/Vis" button is selected. >=5
INCLUDETRIPLETS2 To include triplets in the UV/Vis calculation of singlet wave functions. The intensity of the excitation will be small (zero) but can be useful if interested in all lower energy excited states.
INCLUDESINGLETS2 To include singlet excitations in the UV/Vis calculation of triplet wave functions. The intensity of the excitation will be small (zero) but can be useful if interested in all lower energy excited states.
By default core electrons are not used in post-Hartree-Fock calcultions. Use CORE=THAWED to allow all core electrons to be excited.
N_FROZEN_VIRTUAL=n2 Reduces the number of virtual molecular orbitals used in the calculation. Changing this number from the default, may speed up the calculation, but may also cause inaccuracies in the calculation.
MAX_CIS_CYCLES=n2 To change the number of SCF cycles to try before 'giving up' on the CIS calculation. Increase if you are having convergence problems, but waiting longer might work. 10
CIS_CONVERGENCE=x2 Decrease this number if you want quicker convergence at the cost of precision. (Reducing to a number below 5 can give unphysical results.) 6
CIS_AMPL_PRINT=x To print filled/unfilled molecular orbital pairs which have coefficients larger than x. This value is in hundredths so the default value of 15 implies an amplitude of 0.15. (This will go in the verbose output file, so make sure to use the KEEPVERBOSE keyword.) 15
SET_ITER Controls a convergence limit when converging on the excited states. May be useful if you get the "MaxIt Reached in CIS/RPA iterations" error message. Can also be useful in some IR (frequency) calculations. 31
Keywords related to the NMR calculations
D_SCF_MAX_2=n The maximum number of SCF-NMR steps to try before giving up. Typically, increasing this will allow difficult systems to converge. 75
D_SCF_CONV_2=n The tolerance/precision used in the inner (2nd) part of the convergence algorithm. "n" is the decimal so the default of 2 implies 10-2=0.01. 2
D_SCF_MAX_1=n Maximum number of tries in the inner NMR convergence step. 40
D_SCF_CONV_1=n The tolerance of the inner NMR convergence step. 0
Keywords specific to the coupling constant calculator
(For these keywords to work they must be appended to the JISSC= keyword, comma separated.)
JISSC= This keyword is controlled by the "Coupling Constants" pull-down menu. By default we use some simple "Karplus-like" equations for H-H coupling, but also can be calculated form first principles using either the Fermi-Contact approximation or the full ncalculation. <karplus>
MOPROP_CONV_1ST~n Sets the convergence criterion for second-order TDSCF. "n" is the decimal so the default of 2 implies 10-2=0.01. 6
MOPROP_CONV_2ND~n Sets the convergence criterion for second-order TDSCF. "n" is the decimal so the default of 2 implies 10-2=0.01. 6
MOPROP_MAXITER_1ST~n The maximum number of iterations for CPSCF and first-order TDSCF. 50
MOPROP_MAXITER_2ND~n The maximum number of iterations for second-order TDSCF. 50
Modifying DFT paramters
BIGGRID= There are a number of keywords related changing the grid size used in DFT calculations.
  • SG-1 and SG-0, small grids tuned for the 6-31G* basis sets.
  • SMALLGRID (Spartan's default for "simple" functionals; SG-0 for H,C,N, and O and SG-1 for all other atoms)
  • EMLGRID (50,194)
  • BIGGRID (70,302)
  • VERYBIGGRID (100,434)
  • FINEGRID (99,590)
  • HUGEGRID (250,947)

In the above notation the first number is the number of shells in the radial direction, the second number (i.e. 194, 434 etc.) is the number of Lebedev radial points.

One can also use the BIGGIRD keyword with an equal sign, to enter a Q-Chem like grid notation. Specifically a 12 digit number with the first six (counting leading/implied zeros) defining the number of shells in the radial direction and the next 6 defining the number of Lebedev radial points. i.e., BIGGRID and BIGGRID=70000302 both refer to (70,302)

Valid values for Lebedev grids are:
6, 18, 26, 38, 50, 74, 86, 110, 146, 170, 194, 230, 266, 302, 350, 434, 590, 770, 974, 1202, 1454, 1730, 2030, 2354, 2702, 3074, 3470, 3890, 4334, 4802, 5294.

If you want to use Gauss-Legendre angular points (a=2N^2) instead of Lebedev numbers use BIGGRID=-rrraaaaaa (i.e. use a negative number).

Submission Logic
Force a rerun of the calculation throwing away the current archive but keeping the current coordinates.
With the =ORIGINALCOORDS argument will use the coordinates prior to an optimization if availble.
CPUCNT=n Attempt to use n threads/cores. This will override the thread count assigned by the queueing logic setup by your system administrator. WARNING: This can be abused and in affect "steal" system resources from other jobs/users using the same system so should be used with caution.
The "start from geometry", "IR", "UV/Vis and "NMR" check-boxes in the setup panel can be overriden with these keywords. This is useful if these steps require more keywords. Note that the options to these keywords are comma seperated and any required equal (=) signs must be replace with a tilde (~). Upon hitting the "Enter" key these keywords will "dissapear" and the options will be displayed in the appropriate pull-down menu of the setup panel.
1 Indicates that these should not be typed in as there is a button in the calculation dialogue for it.
2 The keyword is used by a module other than the property module, but is mentioned here for completeness.